The present invention relates to a new process for producing aluminum diacetate monobasic.
Many approaches have described in the literature prior to the present invention for preparing aluminum diacetate monobasic, Al(C2H3O2)2(OH), which is also known as hydroxyaluminum diacetate, monohydroxy aluminum acetate, or monobasic aluminum acetate. V. N. Maksimov, et al., (1) summarizes most of the methods extant in 1960 as does a more brief description in Junixc3xa8re and Sigwalt""s Aluminium, Its Applications in the Chemical and Food Industry (2).
In 1854, W. Crum (3) described the first preparative route to aluminum diacetate monobasic by the double displacement reaction of aluminum sulfate with lead acetate. A similar displacement reaction route using barium acetate and aluminum sulfate was described in 1899 by Ley (4).
The most common preparation of Al(C2H3O2)2(OH) is from aluminum hydroxide (hydrated alumina) and glacial acetic acid (5-8). Sears, U.S. Pat. No. 2,992,262 (9) described a process for making basic aluminum salts, particularly basic aluminum acetates, of short chain carboxylic acids from the reaction of hydrated alumina (i.e., aqueous Al(OH)3) with acetic acid or acetic anhydride, where the acid or anhydride component is introduced in the vapor phase under special conditions.
Another common route for producing aluminum diacetate monobasic is from the reaction of AlCl3 with sodium acetate (10-12). Al(C2H3O2)2(OH) from aluminum chloride and acetic acid has also been described (13), but is a poor synthesis in terms of yield and purity of the product.
A route that uses the action of acetic anhydride on aluminum nitrate was described by Spxc3xa4th in 1912 (14). A preparative route that reacts aluminum metal with acetic acid was described by Seligman in 1916 (15). Merkil further developed the approach from metallic aluminum as described in U.S. Pat. No. 3,957,598 (16).
In 1974, Bumans and Mironovich (17) described that during hydrothermal syntheses of boehmite from the treatment of bayerite or hydrargillite in 1-7 molar acetic acid for 5 hours at 200xc2x0 C., basic aluminum acetates were formed when the acetic acid concentration was increased, and that with 100% acetic acid under the same conditions Al(C2H3O2)2(OH) was formed.
Johnson, U.S. Pat. No. 3,014,055 (18) described a process of forming water soluble complexes of alumina that implies the formation of basic aluminum acetates, although these compositions were made soluble by the incorporation of significant amounts of water soluble, organic, polyhydroxy stabilizing compounds.
Shih, U.S. Pat. No. 3,655,329 (19) described a process for the production of water-soluble, poly aluminum hydroxy (PAH) salts including PAH-acetate. This involved precipitating the PAH compound from a solution of an aluminum halide salt treated with NH4OH, NaOH, or KOH, and then dissolving the PAH compound in one of a selection of acids that includes acetic acid.
U.S. Pat. No. 5,233,065 (20) described a method for producing an aqueous aluminum acetate solution that was stated as being stable to boiling, heating, and aging by the xcex1-hydroxy-carboxylic acid treatment of a composition formed from the reaction of a hydroxychloroaluminum species with glacial acetic acid.
Many of the known processes for preparing aluminum diacetate monobasic are not desirable commercially since they result in a product of low yield or purity, and/or are expensive to produce since they require raw materials that are expensive or are not otherwise available in bulk, or utilize complex, time consuming and/or inefficient processing steps.
The present invention provides a new process for preparing aluminum diacetate monobasic that, unlike many of the processes of the prior art, results in a product of high yield and purity, utilizes raw materials that are inexpensive and readily available commercially, and includes simple and time efficient processing steps. Specifically, the process of the present invention comprises the steps of: (a) agitating a reaction mixture comprising an aqueous acetic solution and a sodium aluminate solution to form aluminum diacetate monobasic and sodium acetate in the reaction mixture; and (b) adding aluminum chloride solution to the reaction mixture in an amount sufficient to react with sodium acetate to obtain a resulting product comprising aluminum diacetate monobasic.
The aluminum diacetate monobasic obtained by the process of the present invention is water-insoluble and thixotropic, and is useful in a number of applications including but not limited to sol-gels, waste water treatment, papermaking, dyeing, polymer formulations, textile manufacturing, and ink formulations.
Additional objects and benefits of the present invention will be apparent from the description which follows.